1. Field of the Invention
The invention relates to methods for treatment of neurological disease by administering an agent which interacts with a retinoid receptor associated with the neurological disease. The invention also relates to a method of modulating dopamine receptor synthesis by introducing an agent that interacts with a retinoid receptor associated with the dopamine receptor synthesis. The invention further relates to a transgenic mouse which is deficient in the normal synthesis of one or more receptors of RARxcex1, xcex2, xcex3 and RXR, and cell line thereof.
2. Related Art
Retinoids
A number of studies have demonstrated that retinoids (vitamin A derivatives) are essential for normal growth, vision, tissue homeostasis, reproduction and overall survival (for reviews and references, see Sporn et al., The Retinoids, Vols. 1 and 2, Spom et al., eds., Academic Press, Orlando, Fla. (1984)). Retinoids are also apparently crucial during embryogenesis, since offspring of dams with vitamin A deficiency (VAD) exhibit a number of developmental defects (Wilson, J. G., et al., Am. J. Anat. 92:189-217 (1953)). With the exceptions of vision (Wald, G., et al., Science 162:230-239 (1968)) and spermatogenesis in mammals (van Pelt, H. M. M., and De Rooij, D. G., Endocrinology 128:697-704 (1991)), most of the effects generated by VAD in animals and their fetuses can be prevented and/or reversed by retinoic acid (RA) administration (Wilson, J. G., et al., Am. J. Anat. 92:189-217 (1953); Thompson et al., Proc. Royal Soc. 159:510-535 (1964)). The dramatic teratogenic effects of maternal RA administration on mammalian embryos (Shenefelt, R. E., Teratology 5, 103-108 (1972); Kessel, M., Development 115:487-501 (1992); Creech Kraft, J., In Retinoids in Normal Development and Teratogenesis, G. M. Morriss-Kay, ed., Oxford University Press, Oxford, UK, pp. 267-280 (1992)), and the marked effects of topical administration of retinoids on embryonic development of vertebrates and limb regeneration in amphibians (Mohanty-Hejmadi et al., Nature 355:352-353 (1992); Tabin, C. J., Cell 66:199-217 (1991)), have contributed to the notion that RA may have critical roles in morphogenesis and organogenesis.
Retinoid Receptors
Except for those involved in visual perception (Wald, G. et al., Science 162:230-239 (1968)), the molecular mechanisms underlying the highly diverse effects of retinoids have until recently remained obscure. The discovery of nuclear receptors for RA (Petkovich et al., Nature 330:444-450 (1987); Giguxc3xa8re et al., Nature 330:624-629 (1987)) has greatly advanced the understanding of how the retinoids may exert their pleiotropic effects (Leid, M., et al., TIBS 17:427-433 (1992); Linney, E., Current Topics in Dev. Biol. 27:309-350 (1992)). It is thought that the effects of the RA signal are mediated through two families of receptorsxe2x80x94the RAR family and the RXR familyxe2x80x94which belong to the superfamily of ligand-inducible transcriptional regulatory factors that include steroid/thyroid hormone and vitamin D3 receptors (for reviews, see Leid, M., et al., TIBS 17:427-433 (1992); Chambon, P., Semin. Cell Biol. 5:115-125 (1994); Chambon, P., FASEB J. 10:940-954 (1996); Giguere, V., Endocrinol. Rev. 15:61-79 (1994); Mangelsdorf, D. J., and Evans, R. M., Cell 83:841-850 (1995); Gronemeyer, H., and Laudet, V., Protein Profile 2:1173-1236 (1995)).
RAR Receptors
Receptors belonging to the RAR family (RARxcex1, xcex2 and xcex3 and their isoforms) are activated by both all-trans- and 9-cis-RA (Leid, M., et al., TIBS 17:427-433 (1992); Chambon, P., Semin. Cell Biol. 5:115-125 (1994); Dollxc3xa9, P., et al., Mech. Dev. 45:91-104 (1994)). Within a given species, the DNA binding (C) and the ligand binding (E) domains of the three RAR subtypes are highly similar, whereas the C-terminal domain F and the middle domain D exhibit no or little similarity. The amino acid sequences of the three RAR subtypes are also notably different in their B regions, and their main isoforms (xcex11 and xcex12, xcex21 to xcex24, and xcex31 and xcex32) further differ in their N-terminal A regions (Leid, M., et al, TIBS 17:427-433 (1992)). Amino acid sequence comparisons have revealed that the interspecies conservation of a given RAR subtype is greater than the similarity found between the three RAR subtypes within a given species (Leid, M., et al., TIBS 17:427-433 (1992)). This interspecies conservation is particularly striking in the N-terminal A regions of the various RARxcex1, xcex2 and xcex3 isoforms, whose A region amino acid sequences are quite divergent. Taken together with the distinct spatio-temporal expression patterns observed for the transcripts of each RAR and RXR subtype in the developing embryo and in various adult mouse tissues (Zelent, A., et al., Nature 339:714-717 (1989); Dollxc3xa9, P., et al., Nature 342:702-705 (1989); Dollxc3xa9 et al., Development 110:1133-1151 (1990); Ruberte et al., Development 108:213-222 (1990); Ruberte et al., Development 111:45-60 (1991); Mangelsdorf et al., Genes and Dev. 6:329-344 (1992)), this interspecies conservation has suggested that each RAR subtype (and isoform) may perform unique functions. This hypothesis is further supported by the finding that the various RAR isoforms contain two transcriptional activation functions (AFs) located in the N-terminal A/B region (AF-1) and in the C-terminal E region (AF-2), which can synergistically, and to some extent differentially, activate various RA-responsive promoters (Leid, M., et al., TIBS 1 7:427-433 (1992); Nagpal, S., et al., Cell 70:1007-1019 (1992); Nagpal, S., et al., EMBO J. 12:2349-2360 (1993)). Knock-outs of RARxcex1, xcex2 and xcex3 have also provided some insight into the physiological functions of these receptors (see, WO 94/26100; Ghyselinck et al., Intl. J. Dev. Biol. 41:425-447 (1997)).
RXR Receptors
Unlike the RARs, members of the retinoid X receptor family (RXRxcex1, xcex2 and xcex3) are activated exclusively by 9-cis-RA (Chambon, P., Semin. Cell Biol. 5:115-125 (1994); Dollxc3xa9, P., et al., Mech. Dev. 45:91-104 (1994); Linney, E., Current Topics in Dev. Biol. 27:309-350 (1992); Leid, M., et al., TIBS 1 7:427-433 (1992); Kastner et al., in Vitamin A in Health and Disease, R. Blomhoff, ed., Marcel Dekker, New York (1993)). However, the RXRs characterized to date are similar to the RARs in that the different RXR subtypes also differ markedly in their N-terminal A/B regions (Leid, M., et al., TIBS 17:427-433 (1992); Leid, M., et al., Cell 68:377-395 (1992); Mangelsdorf et al., Genes and Dev. 6:329-344 (1992)), and contain the same transcriptional activation functions in their N-terminal A/B region and C-terminal E region (Leid, M., et al., TIBS 1 7:427-433 (1992); Nagpal, S., et al., Cell 70:1007-1019 (1992); Nagpal, S., et al., EMBO J. 12:2349-2360 (1993)).
It is currently unclear whether all the molecular properties of RXRs characterized in vitro are relevant for their physiological functions in vivo. In particular, it is unknown under what conditions these receptors act as 9-cis-RA-dependent transcriptional regulators (Chambon, P., Semin. Cell Biol. 5:115-125 (1994)). The knock-outs of RXRxcex1 and RXRxcex2 in the mouse have provided some insight into the physiological functions of these receptors. For example, the ocular and cardiac malformations observed in RXRxcex1xe2x88x92/xe2x88x92 fetuses (Kastner, P., et al., Cell 78:987-1003 (1994); Sucov, H. M., et al., Genes and Dev. 8:1007-1018 (1994)) are similar to those found in the fetal VAD syndrome, thus suggesting an important function of RXRxcex1 in the transduction of a retinoid signal during development. The involvement of RXRs in retinoid signaling is further supported by studies of compound RXRxcex1/RAR mutants, which reveal defects that are either absent or less severe in the single mutants (Kastner, P., et al., Cell 78:987-1003 (1994); Kastner, P., et al., Cell 83:859-869 (1995); Chiba, H., et al., J. Cell Biol. 139:735-747 (1997)). Moreover, it has been shown that activation of RA-responsive promoters likely occurs through RAR/RXR heterodimers rather than through homodimers (Yu, V. C. et al., Cell 67:1251-1266 (1991); Leid, M., et al., Cell 68:377-395 (1992b); Durand et al., Cell 71:73-85 (1992); Nagpal, S., et al., Cell 70:1007-1019 (1992); Zhang, X. K., et al., Nature 355, 441-446 (1992); Kliewer et al., Nature 355:446-449 (1992); Bugge et al., EMBO J. 11: 1409-1418 (1992); Marks et al., EMBO J. 11:1419-1435 (1992); Yu, V. C. et al., Cur. Op. Biotech. 3:597-602 (1992); Leid, M., et al., TIBS 17:427-433 (1992); Laudet and Stehelin, Curr. Biol. 2:293-295 (1992); Green, S., Nature 361:590-591 (1993)). These results strongly suggest that RAR/RXR heterodimers are indeed functional units that transduce the RA signal in vivo, although it is unclear whether all of the suggested heterodimeric combinations occur in vivo (Chambon, P., Semin. Cell Biol. 5:115-125 (1994)). Thus, the basis for the highly pleiotropic effect of retinoids may reside, at least in part, in the control of different subsets of retinoid-responsive promoters by cell-specifically expressed heterodimeric combinations of RAR/RXR subtypes (and isoforms), whose activity may be in turn regulated by cell-specific levels of all-trans- and 9-cis-RA (Leid, M., et al., TIBS 17:427-433 (1992)).
Retinoid Signaling Through RAR/RXR Heterodimers
Nuclear receptors (NRs) are members of a superfamily of ligand-inducible transcriptional regulatory factors that include receptors for steroid hormones, thyroid hormones, vitamin D3 and retinoids (Leid, M., et al., Trends Biochem. Sci. 17:427-433 (1992); Leid, M., et al., Cell 68:377-395 (1992); and Linney, E. Curr. Top. Dev. Biol., 27:309-350 (1992)). NRs exhibit a modular structure which reflects the existence of several autonomous functional domains. Based on amino acid sequence similarity between the chicken estrogen receptor, the human estrogen and glucocorticoid receptors, and the v-erb-A oncogene Krust, A., et al. (EMBO J. 5:891-897 (1986)) defined six regionsxe2x80x94A, B, C, D, E and Fxe2x80x94which display different degrees of evolutionary conservation amongst various members of the nuclear receptor superfamily. The highly conserved region C contains two zinc fingers and corresponds to the core ofthe DNA-binding domain (DBD), which is responsible for specific recognition of the cognate response elements. Region E is functionally complex, since in addition to the ligand-binding domain (LBD), it contains a ligand-dependent activation function (AF-2) and a dimerization interface. An autonomous transcriptional activation function (AF-1) is present in the non-conserved N-terminal A/B regions of the steroid receptors. Interestingly, both AF-1 and AF-2 of steroid receptors exhibit differential transcriptional activation properties which appear to be both cell type and promoter context specific (Gronemeyer, H. Annu. Rev. Genet. 25:89-123 (1991)).
As described above, the all-trans (T-RA) and 9-cis (9C-RA) retinoic acid signals are transduced by two families of nuclear receptors, RAR xcex1, xcex2 and xcex3 (and their isoforms) are activated by both T-RA and 9C-RA, whereas RXR xcex1, xcex2 and xcex3 are exclusively activated by 9C-RA (Allenby, G., et al., Proc. Natl. Acad. Sci. USA 90:30-34 (1993)). The three RAR subtypes differ in their B regions, and their main isoforms (xcex11 and xcex12, xcex21-4, and xcex31 and xcex32) have different N-terminal A regions (Leid, M., et al., Trends Biochem. Sci. 17:427-433 (1992)). Similarly, the RXR subtypes differ in their A/B regions (Mangelsdorf, D. J. et al, Genes and Dev. 6:329-344 (1992)).
The E-region of RARs and RXRs has also been shown to contain a dimerization interface (Yu, V. C., et al., Curr. Opin. Biotechnol. 3:597-602 (1992)). Most interestingly, it was demonstrated that RAR/RXR heterodimers bind much more efficiently in vitro than homodimers of either receptor to a number of RA response elements (RAREs) (Yu, V. C., et al., Cell 67:1251-1266 (1991); Berrodin, T. J., et al., Mol. Endocrinol 6:1468-1478 (1992); Bugge, T. H., et al, EMBO J. 11:1409-1418 (1992); Hall, R. K., et al, Mol. Cell. Biol. 12: 5527-5535 (1992); Hallenbeck, P. L., et al., Proc. Natl. Acad. Sci. USA 89:5572-5576 (1992); Husmann, M., et al., Biochem. Biophys. Res. Commun. 187:1558-1564 (1992); Kliewer, S. A., et al., Nature 355:446-449 (1992); Leid, M., et al., Cell 68:377-395 (1992); Marks, M. S., et al., EMBO J. 11:1419-1435 (1992); Zhang, X. K., et al., Nature 355:441-446 (1992)). RAR and RXR heterodimers are also preferentially formed in solution in vitro (Yu, V. C., et al., Cell 67:1251-1266 (1991); Leid, M., et al., Cell 68:377-395 (1992); Marks, M. S., et al., EMBO J. 11:1419-1435 (1992)), although the addition of 9C-RA appears to enhance the formation of RXR homodimers in vitro (Lehman, J. M., et al., Science 258:1944-1946(1992); Zhang, X. K., et al., Nature 358:587-591(1992)).
It has been shown that activation of RA-responsive promoters likely occurs through RAR/RXR heterodimers rather than through homodimers (Yu, V. C., et al., Cell 67:1251-1266(1991); Leid, M., et al., Cell 68:377-395 (1992b); Durand et al., Cell 71:73-85 (1992); Nagpal, S., et al., Cell 70:1007-1019 (1992); Zhang, X. K., et al., Nature 355, 441-446 (1992); Kliewer et al., Nature 355:446-449 (1992); Bugge et al., EMBO J. 11:1409-1418 (1992); Marks et al., EMBO J. 11:1419-1435 (1992); Yu, V. C. et al., Cur. Op. Biotech. 3:597-602 (1992); Leid, M., et al., TIBS 17:427-433 (1992); Laudet and Stehelin, Curr. Biol. 2:293-295 (1992); Green, S., Nature 361:590-591 (1993)). The RXR portion of these heterodimers has been proposed to be silent in retinoid-induced signaling (Kurokawa, R., et al., Nature 371:528-531 (1994); Forman, B. M., et al., Cell 81:541-550 (1995); Mangelsdorf, D. J., and Evans, R. M., Cell 83:835-850 (1995)), although conflicting results have been reported on this issue (Apfel, C. M., et al., J. Biol. Chem. 270(51):30765-30772 (1995); see Chambon, P., FASEB J. 10:940-954 (1996) for review). The results of these studies strongly suggest that RAR/RXR heterodimers are indeed functional units that transduce the RA signal in vivo (Chambon, P., Semin. Cell Biol. 5:115-125 (1994)). Thus, the basis for the highly pleiotropic effect of retinoids may reside, at least in part, in the control of different subsets of retinoid-responsive promoters by cell-specifically expressed heterodimeric combinations of RAR:RXR subtypes (and isoforms), whose activity may be in turn regulated by cell-specific levels of all-trans- and 9-cis-RA (Leid, M., et al., TIBS 17:427-433 (1992)).
The RXR receptors may also be involved in RA-independent signaling. For example, the observation of aberrant lipid metabolism in the Sertoli cells of RXRxcex2xe2x88x92/xe2x88x92 mutant animals suggests that functional interactions may also occur between RXRxcex2 and the peroxisomal proliferator-activated receptor signaling pathway (WO 94/26100; Kastner, P., et al., Genes and Dev. 10:80-92 (1996)).
Therapeutic Uses of Retinoids
Overview
As retinoic acid is known to regulate the proliferative and differentiative capacities of several mammalian cell types (Gudas, L. J., et al., In The Retinoids, 2nd ed., Sporn, M. B., et al., eds., New York: Raven Press, pp. 443-520 (1994)), retinoids are used in a variety of chemopreventive and chemotherapeutic settings.
The prevention of oral, skin and head and neck cancers in patients at risk for these tumors has been reported (Hong, W. K., et al., N. Engl. J. Med. 315:1501-1505 (1986); Hong, W. K., et al., N. Engl. J. Med 323:795-801 (1990); Kraemer, K. H., et al., N. Engl. J. Med. 318:1633-1637 (1988); Bollag, W., et al., Ann. Oncol. 3:513-526 (1992); Chiesa, F., et al., Eur. J. Cancer B. Oral Oncol. 28:97-102 (1992); Costa, A., et al., Cancer Res. 54:Supp. 7, 2032-2037 (1994)). Retinoids have also been used to treat squamous cell carcinoma of the cervix and the skin (Verma, A. K., Cancer Res. 47:5097-5101 (1987); Lippman S. M., et al., J. Natl Cancer Inst. 84:235-241 (1992); Lippman S. M., et al., J. Natl Cancer Inst. 84:241-245 (1992)) and Kaposi""s sarcoma (Bonhomme, L., et al., Ann. Oncol. 2:234-235 (1991)), and have found significant use in the therapy of acute promyelocytic leukemia (Huang, M. E., et al., Blood 72:567-572 (1988); Castaigne, S., et al., Blood 76:1704-1709 (1990); Chomienne, C., et al., Blood 76:1710-1717 (1990); Chomienne, C., et al., J. Clin. Invest. 88:2150-2154 (1991); Chen Z., et al., Leukemia 5:288-292 (1991); Lo Coco, F., et al., Blood 77:1657-1659 (1991); Warrell, R. P., et al., N. Engl. J. Med 324:1385-1393 (1991); Chomienne, C., et al., FASEB J. 10: 1025-1030 (1996)).
Acute Promyelocytic Leukemia (APL)
A balanced chromosomal translocation, t(15;17), has been identified in most acute promyelocytic leukemia (APL) cells (Larson, A. R., et al., Am. J. Med. 76:827-841 (1984)). The breakpoint for this translocation occurs within the second intron of the RARxcex1 gene (Alcalay, M. D., et al., Proc. Natl. Acad. Sci. USA 88:1977-1981 (1991); Chang, K. S., et al., Leukemia 5:200-204 (1991); Chen, S., et al., Blood 78:2696-2701 (1991) and within two loci of the gene encoding the putative zinc finger transcription factor PML (Goddard, A., et al., Science 254:1371-1374 (1991)). This reciprocal t(15;17) translocation leads to the generation of a PML-RARxcex1 fusion protein which is co-expressed with PML and RARxcex1 in APL cells (see Warrell, R. P., et al., N. Engl. J. Med. 329:177-189 (1993); Grignxc3xa1ni, F., et al., Blood 83:10-25 (1994); Lavau, C., and Dejean, A., Leukemia 8:1615-1621 (1994); de Thxc3xa9, H., FASEB J. 10:955-960(1996)). The PML-RARxcex1 fusion is apparently responsible for the differentiation block at the promyelocytic stage, since (i) it is observed in nearly all APL patients (Warrell, R. P., et al., N. Engl. J. Med 329:177-189 (1993); Grignxc3xa1ni, F., et al., Blood 83:10-25 (1994); Lavau, C., and Dejean, A., Leukemia 8:1615-1621 (1994)), (ii) it inhibits myeloid differentiation when overexpressed in U937 or HL60 myeloblastic leukemia cells (Grignani, F., et al., Cell 74:423-431 (1993)), and (iii) complete clinical remission due to differentiation of the leukemic cells to mature granulocytes upon treatment with all-trans retinoic acid (T-RA) is tightly linked to PML-RARA expression (Warrell, R. P., et al., N. Engl. J. Med. 324:1385-1393 (1991); Lo Coco, R., et al., Blood 77:1657-1659 (1991); Chomienne, C., et al., FASEB J. 10:1025-1030 (1996)). Multiple studies have addressed the possible impact of PML-RARxcex1 fusion protein formation on cell proliferation (Mu, X. M., et al., Mol. Cell . Biol. 14:6858-6867 (1994)) and apoptosis (Grignani, F., et al., Cell 74:423-431 (1993)), AP1 transrepression (Doucas, V., et al., Proc. Natl. Acad. Sci. USA 90:9345-9349 (1993)), and vitamin D3 signaling (Perez, A., et al., EMBO J. 12:3171-3182 (1993)), but the mechanism(s) by which PML-RARxcex1 blocks myeloid cell maturation has remained elusive. Consistent with the aberrant nuclear compartmentalization of PML-RARxcex1 , which adopts the xe2x80x9cPML-typexe2x80x9d location upon RA treatment (Dyck, J. A., et al., Cell 76:333-343 (1994); Weis, K., et al., Cell 76:345-358 (1994); Koken, M. H., et al., EMBO J. 13:1073-1083 (1994)), the currently prevailing hypothesis is that PML-RARxcex1 possesses altered transcriptional properties compared to PML or RARxcex1 and/or may act in a dominant-negative manner (Perez, A., et al., EMBO J. 12:3171-3182 (1993); de Thxc3xa9, H., et al., Cell 66:675-684 (1991); Kastner, P., et al., EMBO J. 11:629-642 (1992)).
Disorders of the Dopamine Signaling Pathway
Dopamine (DA) is one of the major neuromodulators in the central nervous system (CNS), controlling key physiological functions, from coordination of movements to hormone synthesis and secretion. DA functions are exerted through the interaction with five distinct membrane receptors (DA D1, D2, D3, D4 and D5 receptors (D1R, D2R, D3R, D4R and D5R, respectively)) which belong to the family of seven transmembrane domain G-protein-coupled receptors (Gingrich, J. A. and Caron, M. G., Annu. Rev. Neurosci. 16:299-321 (1993)). The DA D2 receptor (D2R) is highly expressed in the CNS and in the pituitary gland. There are two isoforms of this receptor, D2L and D2S, which are generated by alternative splicing from the same gene (Dal Toso, R., et al., EMBO J. 8:4025-4034 (1989)). Both isoforms are expressed in the same tissues and present a similar pharmacological profile (Jackson, D. M. and Weslind-Danielsson, A., Pharmac. Ther. 64:291-369 (1994)). However, they couple to different G-proteins (Montmayeur, J. P. and Borrelli, E., Proc. Natl. Acad. Sci. U.S.A. 88:3135-3139 (1991); Montmayeur, J. P., et al., Mol. Endocrinol. 7:161-170 (1993); Guiramand, J., et al., J. Biol. Chem. 270:7354-7358 (1995)). In contrast to the wide expression of dopaminergic receptors throughout the CNS, DA is synthesized in a small group of mesencephalic neurons located in the substantia nigra and ventral tegmental area. Interestingly, D2Rs are located both pre- and post-synaptically (Civelli, O., et al., Eur. J. Pharmacol. 19:277-286 (1991)), indicating a key role not only in mediating events in the target cells of dopaminergic neurons, but also in controlling the release of DA.
Knock-out of the D2R gene results in a locomotor Parkinsonian-like phenotype and in pituitary tumors in the mouse (Baik, J. H., et al., Nature 377:424-428 (1995); Saiardi, A., et al., Neuron 19:115-126 (1997)). These results underline the importance of the expression of this gene in the control of different physiological functions, while alterations of its expression might be the basis of some human pathologies. Sequence analysis of the D2R promoter has revealed features of a housekeeping promoter (Minowa, T., et al., Biochemistry 31:8389-8396 (1992); Valdenaire, O., et al., Eur. J Biochem. 220:577-584 (1994)). The D2R promoter lacks TATA and CAAT boxes, while multiple Sp1 binding sites are present. Thus, the control of the expression of the D2R gene must involve cell-specific transcription factors. Given that retinoids have important roles in development, it would be of interest to determine if retinoids have a role in neurological diseases.
The present invention provides a method of treating a neurological disease in a subject, the method comprising administering to the subject an effective amount of an agent which interacts with a retinoid receptor associated with the neurological disease. The present invention also provides a method of treating a neurological disease in a subject comprising administering to a subject an effective amount of an agent that is a retinoid agonist or antagonist. The agonist or antagonist may, but is not required to, bind to a retinoid receptor. The neurological disease may be caused by a disorder of the dopamine signaling pathway. The disorder may be due to hyperactivity of the dopamine signaling pathway, for example, schizophrenia. The disorder may be due to hypoactivity of the dopamine signaling pathway, for example, Parkinson""s disease.
The present invention also provides for a method of treating a neurological disease such as, for example, schizophrenia, Parkinson""s disease, anxiety, depression, drug addiction, disorders of cognition, emesis, eating disorders, pituitary tumor, attention deficit-hyperactivity disorder, Tourette""s Syndrome, Huntington""s disease, tardive dyskinesia, Lesch-Nyhan disease and Rett syndrome.
In the present invention, the agent for effecting treatment of the neurological disease may be an agonist or antagonist of said retinoid receptor. The retinoid receptor associated with the neurological disease is selected from RARxcex1, RARxcex2, RARxcex3, and RXR. RXR includes RXRxcex1, RXRxcex2 and RXRxcex3. The agent may interact with one or more, or a combination of two or more receptors selected from the group consisting of RARxcex1, RARxcex2, RARxcex3, RXRxcex1, RXRxcex2 and RXRxcex3. The agent may interact with RARxcex1/RXRxcex3, RARxcex2/RXRxcex2, RARxcex2/RXRxcex3, or RXRxcex2/RXRxcex3.
The present invention further provides a method of modulating dopamine receptor synthesis in a subject, the method comprising introducing to the subject, an agent that interacts with a receptor selected from the group consisting of RARxcex1, RARxcex2, RARxcex3 and RXR. The dopamine receptor may be selected from the group consisting of D1R, D2R, D3R, D4R and D5R. The present invention provides for a method of increasing dopamine receptor synthesis in a subject, the method comprising introducing to the subject, an agent that is an agonist of a receptor selected from the group consisting of RARxcex1, RARxcex2, RARxcex3 and RXR. The invention further provides for a method of decreasing dopamine receptor synthesis in a subject, the method comprising introducing to the subject, an agent that is an antagonist of a receptor selected from the group consisting of RARxcex1, RARxcex2, RARxcex3 and RXR.
The present invention additionally provides a method of treating a neurological disease or neurological state linked to a dysfunction of dopaminergic systems by providing an effective amount of a retinoid agonist. An example of a neurological disease linked to a dysfunction of dopaminergic systems is Parkinson""s disease.
In addition, the invention provides a method of treating a neurological disease or neurological state that results in hyperlocomotion by providing an effective amount of a retinoid antagonist. In particular embodiments of this invention, a neurological disease or a neurological state that results in hyperlocomotion is drug abuse, e.g., use of cocaine or its derivatives. In more particular embodiments of the invention, the neurological disease or neurological state is cocaine abuse.
The invention further provides for a transgenic non-human animal, such as a rodent, which has been genetically altered such that the animal is deficient in the normal synthesis of one or more, or two or more receptors selected from the group consisting of RARxcex2, RARxcex3, RXRxcex2 and RXRxcex3. The animal may not synthesize detectable levels of one or more receptors selected from the group consisting of RARxcex2, RARxcex3, RXRxcex2, and RXRxcex3. The animal may not synthesize one or more functional receptors selected from the group consisting of RARxcex2, RARxcex3, RXRxcex2, and RXRxcex3. The animal may be heterozygous or homozygous for a deficiency in the normal synthesis of one or more receptors selected from the group consisting of RARxcex2, RXRxcex3, RARxcex2/RXRxcex2, RARxcex2/RXRxcex3 and RXRxcex2/RXRxcex3. In a particular embodiment of this invention, the transgenic animal is a transgenic mouse.
The invention is also directed to a transgenic non-human animal, such as a rodent, which has been genetically altered such that the animal is heterozygous or homozygous for a deficiency in the normal synthesis of a combination of two receptors selected from the group consisting of RARxcex1/RARxcex2, RARxcex2/RARxcex3, RARxcex1/RXRxcex1, RARxcex3/RXRxcex1 and RARxcex1/RXRxcex3.
The above mentioned transgenic animal may contain a heterozygous or homozygous disruption in the endogenous gene encoding the above mentioned retinoid receptor, wherein the disruption comprises the insertion of a selectable marker sequence, and wherein the disruption results in the lack of expression of the receptor and confers a phenotype.
Also provided in the present invention is a mammalian cell line which is heterozygous or homozygous for a deficiency in the normal synthesis of one or more, or two or more receptors selected from the group consisting of RARxcex2, RARxcex3, RXRxcex2, and RXRxcex3. In one embodiment of the invention, the cell line does not synthesize detectable levels of one or more receptors selected from the group consisting of RARxcex2, RARxcex3, RXRxcex2, and RXRxcex3. In another embodiment, the cell line does not synthesize one or more functional receptors selected from the group consisting of RARxcex2, RARxcex3, RXRxcex2, and RXRxcex3. The invention further provides for a cell line that is deficient in the normal synthesis of one or more receptors selected from the group consisting of RARxcex2, RXRxcex3, RARxcex2/RXRxcex2, RARxcex2/RXRxcex3 and RXRxcex2/RXRxcex3. The cell line may be derived from a pluripotent cell line having the ATCC designation CRL 11632.
The invention is also directed to a mammalian cell line, which has been genetically altered such that the mammalian cell line is heterozygous or homozygous for a deficiency in the normal synthesis of a combination of two receptors selected from the group consisting of RARxcex1/RARxcex2, RARxcex2/RARxcex3, RARxcex1/RXRxcex1, RARxcex3/RXRxcex1 and RARxcex1/RXRxcex3.
The above mentioned mammalian cell line may contain a heterozygous or homozygous disruption in the endogenous gene encoding the above mentioned retinoid receptor, wherein the disruption comprises the insertion of a selectable marker sequence, and wherein the disruption results in the lack of expression of the receptor.